|01-30-2014, 06:01 AM||#1|
Join Date: Jun 2013
Device: EZReader Pocket Pro
Converting (Kobo) epubs to reduce file size?
Does anyone know of any method to reduce the bloated filesizes of Kobo epubs? I'm talking 2-3 MB per book (from Kobo), as opposed 250-350 KB (From other sources, such as OmniLit). I was thinking the Convert Book option would do it, but although I've been able to fix some of the other issues (ie, fonts that grow and shrink every couple of paragraphs), nothing I've done so far has significantly changed the file size.
|01-30-2014, 07:58 AM||#2|
Join Date: Aug 2009
Location: The (original) Silicon Valley, USA
Device: Galaxy Tab 2, Astak Pocket Pro, K4NT
THEN make a plan
|01-30-2014, 11:26 AM||#3|
Join Date: Sep 2009
Device: Sony PRS-350, PB360, Kobo Glo/AuraHD/Aura6"
It may well be because the html files in Kobo-style epubs (kepubs) are full of extra <span> tags, e.g. <span class="koboSpan" id="kobo.32.1">some paragraph text</span>. These wouldn't be removed by a calibre conversion as it is perfectly valid code. A long book may have many thousands of them, which adds up.
As theducks says, if you open one up you can see them. With a bit of fancy Regex search/replace all you may be able to remove them to turn the kepub back to a standard epub, but the risk of deleting actual book content makes this rather risky and I wouldn't recommend it.
Edit: The other likely suspects are embedded fonts and/or a lot of images.
Last edited by jackie_w; 01-30-2014 at 11:32 AM.
|02-06-2014, 01:34 PM||#4|
Join Date: Dec 2008
Location: Lancashire, U.K.
Device: BeBook 1, BeBook Pure, Kobo Glo, Various Android Apps
A total size of 2-3Mb is likely to be, as mentioned, embedded fonts, assuming that both the Kobo and the OmniLit books both have the same images (or none at all).
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